Unitary heating system



June 7, 1966 MOCLANAHAN T 3,254,839

UNITARY HEATING SYSTEM Filed July 5, 1963 fiernara A. dial/0046 James A Fuss e/I,

INVENTORS.

BY 6w! M '22 'L H E CITY 32 WATFR United States Patent 3,254,839 UNITARY HEATING SYSTEM Bernard E. McClanahan, La Habra, and James A. Russell, Downey, Calif., assignors to Ace Tank and Heater Company, a corporation of California Filed July 5, 1963, Ser. No. 292,961 2 Claims. (Cl. 237-8) This invention relates to heating systems, and more particularly to a unitary arrangement for heating water for a variety of uses.

The present invention is particularly directed to a hot Water heating system which is arranged to heat water for domestic use, swimming pool heating, and the like, in conjunction with a residential heating system of the hot water type. In general, heating systems of this type, as previously known, have included a boiler or other type of central water heating source and a number of radiators or radiant heating units for providing heat in selected 10- cations, together with the requisite piping and plumbing needed to interconnect the respective elements. An essential component of such a system is an expansion tank which is arranged to enclose a cushion of air and is needed to accommodate the variations in volume of the water in the system over the range of temperatures encountered in normal operation. In heating systems of the type described, it is not uncommon to incorporate in the boiler of the system a heat exchanger coil which is coupled to the domestic hot water system for providing domestic hot water as desired. While such a system generally provides hot water in sufficient quantity'for normal domestic use, it is subject to certain inefticiencies resulting from its structural configuration. During periods when the hot water is not being circulated through the residential heating system, as, for example, in the summer time or during the ott-period of the regular heating cycle, the circulation of water within the boiler itself is substantially limited. The result is that when domestic hot water is drawn under such conditions, the water of the boiler adjacent the heat exchanger coil is rapidly cooled so that the temperature of the water being provided to the user is reduced undesirably.

A further disadvantage of systems of the type described result-s from the fact that the expansion tank, which is an essential part of any heating system of a hot water type, is generally separate from the boiler and therefore must be connected into the system on the site. This necessitates additional expense and labor and materials without any corresponding increase in the effectiveness of the system.

When consideration is 'given to the multiple usesand demands for hot water in some residential arrangements, as, for example, in a home in which hot water is used for heating the home, for domestic use, for heating a swimming pool, for melting ice on sidewalks and driveways, and the like, it can be 'seen that substantial duplication of heating units may occur. Even where some saving in space and expensive equipment may be realized from the combination of a single boiler used for both space heating and for domestic hot water, it is still customary to have separate heating units for heating a swimming pool and for providing hot water to melt ice and snow on a driveway or sidewalk.

It is therefore a general object of the present invention to provide a multipurpose water heating unit arranged to provide hot water for a variety of uses.

It isalso an object of the present invention to provide a water heating unit which is more compact and less expensive than the several units which have heretofore been required to achieve similar results.

An additional object of the present invention is to provide a combination heating system and domestic hot wa- 3,254,839 Patented June 7, 1966 ter heat source which is more efiicient than previously known arrangements for serving such a purpose.

It is a still further object of the present invention to provide a heating system hot water heater which includes as an integral part thereof the expansion tank which is a necessary component of the overall system.

In brief, particular arrangements in accordance with the present invention comprise a water heater, or primary heat exchanger, coupled in a closed circulating system to an integrally mounted expansion tank, and a circulating pump. Within the expansion tank and suitably mounted within the stream of hot water as it circulates therethrough there are positioned secondary heat exchanging coils which may be coupled to provide hot water for domestic and other uses. These arrangements in accordance with the invention are provided with suitable couplings and connections for hook-up to electric, gas, and water systems in the conventional home, and are provided with the necessary controls to operate the various systems automatically and with a minimum of attention. cordance with one aspect of the invention, a pressure controlling mechanism is provided which precludes the possibility of swimming pool water which is passing through one of the secondary heat exchanging coils coming in contact with the water which is being heated for domestic use. In accordance with another aspect of the invention, secondary heat exchanging coils are allotted within the expansion tank in an arrangement which permits the ready replacement of coils, should repairs ever'be needed, or permits one coil to be removed and a plurality of coils to be substituted in its place. In accordance with a further aspect of the invention, a circulating pump mentioned above is arranged to run continuously, thus assuring continu'al circulation of water in the closed system between the primary heat exchanger and the expansion tank, so that the secondary heat exchanging coils within the exexpansion tank are always surrounded with hot water at or near the maximum temperature for which the system is set. This same circulating pump advantageously supplies hot water to the house heating system under the control of room thermostats during the heating season.

In one particular arrangement in accordance with the invention, a variable temperature mixing valve is provided to mix cold water with the water from one of the secondary heat exchanging coils so as to provide hot water for domestic use at a preselected temperature below the temperature of the boiler water. A temperature sensing element is connected in the closed circulating systems as a safety feature to cut ofl the supply of gas or other fuel to the primary heat exchanger burner in the event that the flow of water in the circulating system ceases, as might occur in the event of a failure of operation of the circulating pump, or when water in the system drops below a safety level. The unitary heater of the present invention also includes a connection from the cold water inlet of one of the secondary heat exchanging coils to the closed circulating portion of the system through pressure regulating and relief valves, thereby eliminating the necessity for a separate connection to feed water to the circulating system from the house supply.

A better understanding of the present invention may be had from a consideration of the following detailed description, taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a pictorial representation of one particular arrangement in accordance with the invention;

FIG. 2 is a schematic representation of the arrangement of FIG. 1;

FIG. 3 is a cutaway view of a particular portion of the arrangement shown in FIG. 1; and

FIG. 4 is a bottom view of the portion shown in FIG. 3.

In ac-' In the pictorial representation of FIG. 1, a unitary heating system 18 in accordance with the invention is shown comprising a boiler 11 coupled to an expansion tank 12 and a pump 14 by appropriate piping to define a complete water circulating system. The boiler 11 may be a conventional water heating boiler including a gas burner (not shown), an exhaust port 16, a water chamber (also not shown) to which heat is transferred from the burning gases in the burner, and suitable control and regulator valves 18, 19 and 20 to control the supply of fuel to the burner. The circulating pump 14 is driven by an electric motor 15 which is designed, in accordance with an aspect of the invention, to run continuously so that the hot water is continuously circulating from the boiler 11 to the expansion tank 12 and back. The expansion tank 12, which is an essential part of any residential heating system using water as the heat transfer medium, is provided as an integral part of the heating system of the invention so that installation is considerably simplified, requiring connection only to the various water,

fuel and electric lines.

A thermometer 24 and a water glass 22, the latter being con-nected between valves 23, are afl'lxed to the side of the expansion tank 12 for registering the temperature and level of the water in the expansion tank 12. Openings 26 and 27 are provided in the water line on opposite sides of the pump 14 to permit connection to Water lines leading to the radiators or radiant heating lines which are installed in the house as part of the house heating system. A support leg 28, which may advantageously be flanged pipe threaded to screw into a coupling on the underside of the expansion tank 12, is shown extending downwardly therefrom. A thermostat assembly 38 is shown coupled in the line of the water circulation system leading from the boiler 11 to the expansion tank 12 and is connected to control the gas valve 18 in accordance with the temperature of the water as sensed by the thermostat 38 relative to the temperature setting thereof.

A schematic diagram of the system of FIG. 1 is shown in FIG. 2 wherein corresponding elements are designated by like reference numerals. In addition, the further details of the system as it is connected for operation in a typical installation are shown. In addition to the items which are shown in FIG. 1, the diagram of FIG. 2 shows a water mixing valve 32 adjacent the expansion tank 12 coupled to receive water via a pipe 38 from a city .water main and to deliver hot water at a selected temperature to a pipe leading to a domestic hot water distribution system. The mixing valve 32 is connected via short pipes to threaded couplings 34 extending from the bottom of the expansion tank 12. A pair of pipes 37 extend from similar couplings 36, also at the underside of the expansion tank 12, and are shown connected to provide water for a swimming pool heating system, although this connection may alternatively be used to provide hot water for melting snow on a driveway or sidewalk or for other similar uses. A water line 39 is shown extending from the city water main pipe 38 via a pressure control valve 40 to the boiler 11 and is used to supply water for the boiler 11 at a pressure which is reduced below the water main pressure.

The expansion tank 12 is shown in further detail in FIGS. 3 and 4 and, in the cutaway view of FIG. 3, is indicated as including a pair of heating coils 46 and 47 which are coupled respectively to the openings 34 and 36 to provide hot water for various individual uses. Although in this particular embodiment only two heating coils are shown within the expansion tank 12, it will be understood that a greater plurality of such coils may be included it hot water is needed for other uses in addition to those shown, simply by providing a larger expansion tank or using coils of reduced diameter. The heating coils 46 and 47 serve as secondary heat exchangers to extract heat from the water being circulated from the boiler 11 through the expansion tank 12. The bottom portion of the expansion tank 12 comprises a plate 42 which isremo-vably secured to a flange 43 on the expansion tank 12 by means of a plurality of bolts 44. By means of this arrangement, the plate 42 may be easily removed in order that one or another of the heating coils 46, 47 may be replaced or installed as desired, thus considerably simplifying the problem of cleaning, repairing or replacing the respective heating coils. If called for, the expansion tank 12 may be installed without one or both of the heating coils 46, 47. Atlernatively, the expansion tank 12 may be provided with both coils 46, 47 installed therein but need not be used for connection via the couplings 34, 36 to individual hot water distribution systems. If one or both of the coils 46, 47 is not connected past the couplings 34, 36, these openings may be capped if desired to prevent the entry of dirt or accumulation of other debris. 4

In the operation of the depicted system in accordance with the invention, the thermostat 30 is adjusted to the desired temperature setting, the pump motor 15 is energized to run the pump 14 continuously, and the gas control valve 20 is turned on. Boiler water is admitted via the line 39 by adjusting the pressure regulating setting of the pressure control valve 48* with the water glass valves 23 opened until the water level is seen to rise in the water glass 22 to a point approximately midway between the valves 23. This setting will provide, in accordance with an aspect of the invention, a pressure level in the boiler and associated hot water circulation system including the expansion tank 12 which is lower than the city main pressure present in the line 38 but at some level above the maximum pressure which will be encountered in the line 37 coupled to the swimming pool water heating system. Operating in this fashion, the pump 14 propels water continuously through the expansion tank 12 to flow with substantial turbulence about the heating coils 46, 47 so that these coils are advantageously maintained at or very near the temperature of the water circulating between the boiler 11 and the ex pansion tank 12. In accordance with an aspect of the invention, hot water from the boiler 11 is first directed to the heating coils 46, 47 before it is supplied to the residential heating system so that water at maximum temperature is available for the domestic hot water system. Moreover, because of this continuous circulation of water, the temperatures of water in the expansion tank 12 and in the boiler 11 are maintained substantially uniform without a significant temperature gradient. Heat extracted from the water in the expansion tank 12 by the secondary heat exchanging coils 46, 47 is thus available for delivery by the flow of water therethrough to the domestic hot water heating system and to the swimming pool heating system or any other systems which may be similarly connected. In addition, whenever heat is needed for the house heating system coupled to the openings 26, 27, water is circulated therethrough by the pump 14 as demanded under the control of room thermostats (not shown). As domestic hot water is drawn, it is mixed with city water from the line 38 in the mixing valve 32 in accordance with the temperature setting thereof. The fiow of fuel to the burner in the boiler 11 is controlled in accordance with the temperature of the circulating water as sensed by the thermostat 30. When the water temperature drops below a preset level, the

I thermostat 30' opens the valve 18 so that the burner is supplied with fuel and when the water temperature rises above a predetermined maximum setting, the thermostat 30 acts to control the valve 18, thus cutting off the supply of fuel to the burner.

By virtue of the advantageous arrangement of the invention as described above, a virtually unlimited supply of hot water is made available for domestic use and for swimming pool heating or for any other systems which may be similarly connected to the secondary heat exchange coils 46, 47 within the expansiontank 12. This is made possible in an efiicient manner by means of the depicted arrangement which insures the continuous flow of hot water past the heat exchanging coils 46, 47 Without any significant temperature gradient from the temperature of the water within the boiler 11 and, further, because of the fact that the entire water heating capacity provided for the house heating system coupled to the openings 26, 27 is available, if needed, for the heating of water for other distribution systems including the domestic hot water system. The entire system is provided in a compact and efiicient arrangement which comprises the expansion tank 12 with the heat exchanging coils 46, 47 in a single unit fastened directly to the boiler I11 in a unitary package which is ready for installation simply by connection to the respective Water, gas and electric lines in the users building. By virtue of this compact and eflicient arrangement in accordance with the invention a packaged unitary water heating system is provided in a space only slightly larger than that normally required by a conventional domestic hot water heater. By virtue of the combination of a number of different individual heating systems coupled to one heat source, the present invention provides an improved and economical water heating system which achieves lower initial cost and substantially reduced operating costs as compared with those systems presently in use which require independent heat sources for each independent system.

A further important aspect of this invention relates to the fact that the pressure of the water circulating within the boiler 11 and the expansion tank 12 is maintained within a range which lies between the city water main pressure and the maximum pressure of a swimming pool heating system. Heretofore there has been serious objection to the combination of a swimming pool heating system with a domestic hot water heating system coupled to the same heat source because of the possibility of a rupture in the respective systems permitting the intermixture and transfer of water from the swimming pool system to the domestic hot water heating system. The present invention, however, maintains a relationship of respective pressures in the various independent systems such that, should such a rupture occur, water will flow out of the domestic hot water heating coil which is maintained at city-water main pressure into the boiler water circulation system which is at a reduced pressure and thence into the heating coil coupled to provide hot water for the swimming pool system which is at the lowest pressure of all, rather than in the opposite direction. This particular aspect in accordance with the invention absolutely precludes the possibility of water flowing from the swimming pool into the domestic hot water system, and thus permits the combination of the various heating systems with a single heat source with complete safety.

Although there has been described above a specific arrangement of a unitary water heating system in accordance with the invention for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements falling within the scope of the annexed claims should be considered to be a part of the invention.

What is claimed is:

1. A water heating arrangement including a boiler, an expansion tank and a pump for coupling into a unitary closed circulation system, a first heat exchanging means and a second heat exchanging means positioned within the expansion tank and immersed in water therein for coupling into first and second independent auxiliary hot water systems respectively, and means for maintaining said first heat exchanging means at a high pressure, said expansion tank at an intermediate pressure, and said second heat exchanging means at a low pressure to insure a predetermined flow pattern upon fluid tight integrity failure of the heat exchanging means.

2. A water heating arrangement as defined in claim 1 and including means for driving said pump continuously in order to maintain a steady flow of water about the heat exchanging means.

References Cited by the Examiner UNITED STATES PATENTS 1,708,449 4/ 1929 Martin 2378 2,327,339 8/ 1943 Chandler 237-8 2,607,535 8/1952 Moore 2378 2,721,706 10/1955 Schoerner 237-8 2,781,174 2/1957 Smith 126-362 X 2,813,683 11/1957 Dillman 237-8 2,841,337 7/1958 Haugen 237-8 3,139,867 7/1964 Cleaver et al' 1225l0 X EDWARD J. MICHAEL, Primary Examiner.

M. L. BATES, Assistant Examiner. 

1. A WATER HEATING ARRANGEMENT INCLUDING A BOILER, AN EXPANSION TANK AND A PUMP FOR COUPLING INTO A UNITARY CLOSED CIRCULATION SYSTEM, A FIRST HEAT EXCHANGING MEANS AND A SECOND HEAT EXCHANGING MEANS POSITIONED WITHIN THE EXPANSION TANK AND IMMERSED IN WATER THEREIN FOR COUPLING INTO FIRST AND SECOND INDEPENDENT AUXILIARY FOR WATER SYSTEMS RESPECTIVELY, AND MEANS FOR MAINTAINING SAID FIRST HEAT EXCHANGING MEANS AT A HIGH PRESSURE, SAIF EXPANSION TANK AT AN INTERMEDIATE PRESSURE AND SAID SECOND HEAT EXCHANGING MEANS AT A LOW PRESSURE TO INSURE A PREDETERMINED FLOW PATTERN UPON FLUID TIGHT INTEGRITY FAILURE OF THE HEAT EXCHANGING MEANS. 